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CASE STUDY
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Returning to our farm “ Happy Abs ”
You have now been called out to the farm to investigate as the situation is not resolving and deaths continue to occur . You collect a range of samples ( affected and unaffected animals ) to take to the laboratory ( see “ Sample submission ” on page 67 ).
Looking at the data , we have confirmed there is an outbreak on the farm based on the much higher than usual incidence of mortality and comparative attack rates in two tanks . We were initially working with the very broad case definition of “ dead abalone ”. When you arrive on the farm you note the following clinical signs in affected abalone ; enlarged mouth , a curled foot and protruding radula ( tongue ) see Figures 5 and 6 .
The new animal level case definition is updated to – a deceased abalone displaying a curled foot , enlarged mouthparts and protruding radula . This definition is appropriate if all abalone are displaying these clinical signs . A broader definition could include all dead abalone and live abalone with the clinical signs if we know that some abalone will die very quickly without signs . At a tank level , a “ case tank ” could be defined as “ a tank having daily mortality over 2 per cent for two or more consecutive days ”. The specific clinical syndrome could also be included in the tank level definition .
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